This is an improvement in the filter tubes disclosed in Harms U.S. Pat. No. 3,503,516 issued Mar. 31, 1970 and Harms U.S. Pat. No. 3,720,322 issued Mar. 13, 1973, and adapting such filter tubes for an assembled array, such as disclosed in McEwen U.S. Pat. No. 3,935,105 issued Jan. 27, 1976.
Although it is well known to have filter tubes with perforated inner tubes, fabric socks, and axial compression springs to press them into engagement with an aperture in a suction duct or chamber, there is no known filter tubes having the specific parts and structure invented by applicants for such easy replacement in a tubular filter array of the type disclosed in said above mentioned McEwen U.S. Pat. No. 3,935,105.